Adaptive HARQ for half duplex operation for battery and antenna constrained devices

ABSTRACT

A user equipment (UE) implements improved communication methods which enable uplink (UL) transmissions consistent with an UL timeline. The UE may have a transmit duty cycle and may transmit acknowledge/negative acknowledge messages to a base station according to the transmit duty cycle. Additionally, the UE may be configured to determine signal-to-interference-plus noise ratio (SINR) between the UE and the base station and compare SINR to a threshold. The UE may transmit redundancy versions of data in consecutive sub-frames with a duty cycle of two transmissions per X+1 sub-frames if SINR is equal or above the threshold and redundancy versions using a duty cycle of one transmission per X sub-frames if SINR is below the threshold. Further, the UE may be configured to communicate a number of UL HARQ processes supported by the UE, receive first information in a first sub-frame, and send second information X sub-frames after the first sub-frame.

PRIORITY DATA

This application claims benefit of priority to U.S. ProvisionalApplication Ser. No. 62/066,282, titled “Half Duplex Operation forBattery and Antenna Constrained Devices”, filed Oct. 20, 2014 by TarikTabet and Syed Aon Mujtaba and U.S. Provisional Application Ser. No.62/069,787, titled “Adaptive HARQ for Half Duplex Operation for Batteryand Antenna Constrained Devices”, filed Oct. 28, 2014 by Tarik Tabet andSyed Aon Mujtaba, which are hereby incorporated by reference in theirentirety as though fully and completely set forth herein.

FIELD

The present application relates to wireless communication, and moreparticularly, adaptive hybrid automatic repeat request (HARQ) for halfduplex operations for battery and antenna constrained devices in a radioaccess technology such as LTE.

DESCRIPTION OF THE RELATED ART

Wireless communication systems are rapidly growing in usage.Additionally, there exist numerous different wireless communicationtechnologies and standards. Some examples of wireless communicationstandards include GSM, UMTS (WCDMA, TDS-CDMA), LTE, LTE Advanced(LTE-A), HSPA, 3GPP2 CDMA2000 (e.g., 1×RTT, 1×EV-DO, HRPD, eHRPD), IEEE802.11 (WLAN or Wi-Fi), IEEE 802.16 (WiMAX), Bluetooth, etc.

In cellular radio access technologies (RATs) such as LTE, the userequipment (UE) requests uplink (UL) resources by means of a schedulingrequest (SR). In response to a SR, the base station assigns UL resourcesto the UE with a UL grant. The base station can assign resources to theUE on every sub-frame. After the UE receives a UL grant, the UE cantransmit data to the base station on the physical uplink shared channel(PUSCH).

Hybrid automatic repeat request (HARQ) is a technique used by a receiverto detect a corrupted message and to request a new message from thesender. In LTE frequency division duplexing (FDD) the UL HARQ issynchronous, i.e., if the UL grant for the initial transmission isreceived by the UE at t=0, the UL transmission on PUSCH occurs at t=4,the ACK/NACK feedback occurs on t=8 and the HARQ retransmission occurson t=12. In order to obtain a grant, the UE sends a scheduling request(SR) to the base station (e.g., at t=0), and the base station will senda UL grant in the PDCCH at t>=4.

A device which is peak current limited (i.e., a device that has limitedbattery and/or limited power amplifier capability) may not able totransmit continuously in the UL, e.g., it can transmit only on a lowduty cycle. A device may be peak current limited because of the size ofits battery (e.g., the device may only have a finite amount of currentthat may be drawn from the batter) and/or because of the efficiency ofits antenna (e.g., in order to maintain connectivity with the basestation, the antenna's power amplifier may need to operate at maximumoutput). Additionally, a device may have restrictions similar to a peakcurrent limited device because of half duplex frequency division duplex(FDD) operation (e.g., when concurrent transmit and receive is notsupported).

For example, devices constrained due to battery size and/or antennaefficiency may transmit during one sub-frame and then may remain silentfor the next 7 sub-frames for FDD transmissions and the next 9sub-frames for time division duplexing (TDD) transmissions. Thus, as onecommon example, such a device may transmit only in one sub-frame per LTEradio frame. The duty cycle in the FDD case is 12.5% and in the TDD caseis 10%.

A mechanism is needed to enable UL transmissions in such scenarios andto make sure that the UE may still transmit in the UL without violatingthe UL timeline. Therefore, improvements in the field would bedesirable.

SUMMARY

Embodiments are presented herein of, inter alia, a user equipment (UE),base station (eNB), and improved communication methods which enable a UEthat is peak current limited to maintain an uplink timeline.

Some embodiments relate to a user equipment device (UE) comprising atleast one antenna, at least one radio, and one or more processorscoupled to the radio. The at least one radio is configured to performcellular communication using at least one radio access technology (RAT).The one or more processors and the at least one radio are configured toperform voice and/or data communications, as well as the methodsdescribed herein.

In some embodiments, the UE is configured to transmit first user dataand a first acknowledge/negative acknowledge (ACK/NACK) in a firstsub-frame subsequent to receiving first data from a base station Ysub-frames prior to the transmission of the first user data. The firstACK/NACK may correspond to the first data from the base station and theUE has a transmit duty cycle of X sub-frames, where X is greater than Y.Additionally, the UE is configured to transmit second user data and asecond ACK/NACK in a second sub-frame subsequent to receiving seconddata from the base station Y sub-frames prior to transmission of thesecond user data. The second ACK/NACK may correspond to the second datafrom the base station. The second sub-frame is X sub-frames after thefirst sub-frame.

In another embodiment, the UE is configured to determinesignal-to-interference-plus noise ratio (SINR) for a channel between theUE and a base station and compare the SINR to a threshold. When the SINRis greater than or equal to the threshold, the UE may transmit, inconsecutive sub-frames, a first version and a second version of userdata. Additionally, the UE may transmit, in consecutive sub-frames, athird version and a fourth version of user data. The transmission of thethird version may occur X+1 sub-frames after transmission of the firstversion, where the UE may have a transmit duty cycle of X sub-frames.Additionally, when the SINR is less than the threshold, the UE maytransmit the first version of the user data in a first sub-frame andtransmit the second version of the user data in a second sub-frame andthe second sub-frame may occur X sub-frames after the first sub-frame.

In some embodiments, the UE is configured to communicate, to a basestation, a number of uplink (UL) hybrid automatic repeat request (HARQ)processes supported by the UE, receive first information from the basestation in at least a first sub-frame, and send second information tothe base station X sub-frames after the first sub-frame. The firstinformation may correspond to at least a first downlink (DL) HARQprocess and a number of DL HARQ processes depends upon the number of ULHARQ processes. The second information may include a first ACK/NACKassociated with the first DL HARQ process.

Some embodiments relate to a base station comprising a radio and aprocessing element operatively coupled to the radio. The radio andprocessing element are configured to perform wireless communication witha wireless device (e.g. a UE), as well as the methods described herein.

In some embodiments, the base station is configured to receive, from awireless device, a number of uplink (UL) hybrid automatic repeat request(HARQ) processes supported by the wireless device, send firstinformation to the wireless device in at least a first sub-frame, andreceive second information to the base station X sub-frames after thefirst sub-frame. The first information corresponds to at least a firstdownlink (DL) HARQ process and a number of DL HARQ processes dependsupon the number of UL HARQ processes. The second information includes afirst ACK/NACK associated with the first DL HARQ process.

This Summary is intended to provide a brief overview of some of thesubject matter described in this document. Accordingly, it will beappreciated that the above-described features are merely examples andshould not be construed to narrow the scope or spirit of the subjectmatter described herein in any way. Other features, aspects, andadvantages of the subject matter described herein will become apparentfrom the following Detailed Description, Figures, and Claims.

BRIEF DESCRIPTION OF THE DRAWINGS

A better understanding of the present subject matter can be obtainedwhen the following detailed description of the embodiments is consideredin conjunction with the following drawings.

FIG. 1 illustrates an exemplary wireless communication system, accordingto some embodiments.

FIG. 2 illustrates a base station (“BS”, or in the context of LTE, an“eNodeB” or “eNB”) in communication with a wireless device, according tosome embodiments.

FIG. 3 illustrates a block diagram a wireless communication system,according to some embodiments.

FIG. 4 illustrates a block diagram of a base station, according to someembodiments.

FIG. 5A illustrates traditional TTI bundling, according to the priorart;

FIG. 5B illustrates an LTE UL HARQ procedure, according to the priorart;

FIG. 6 illustrates an exemplary timeline of a HARQ process, according tosome embodiments;

FIG. 7 illustrates an exemplary timeline for improving the downlinkbudget, according to some embodiments;

FIG. 8 illustrates another exemplary timeline for improving the downlinkbudget, according to some embodiments;

FIG. 9 illustrates an exemplary timeline for multiple uplink HARQprocesses, according to some embodiments;

FIG. 10 illustrates an exemplary timeline for multiple uplink anddownlink HARQ processes and TTI bundling, according to some embodiments;

FIG. 11 illustrates an exemplary timeline for multiple downlink anduplink HARQ processes, according to some embodiments;

FIG. 12 illustrates a method for HARQ signaling, according to someembodiments;

FIG. 13 illustrates a method for HARQ signaling, according to someembodiments;

FIG. 14 illustrates an exemplary timeline for TTI bundling and connecteddiscontinuous reception cycle (C-DRX), according to some embodiments;

FIG. 15 illustrates a method for distributed TTI bundling, according tosome embodiments; and

FIG. 16 illustrates a method for distributed TTI bundling, according tosome embodiments.

While the features described herein are susceptible to variousmodifications and alternative forms, specific embodiments thereof areshown by way of example in the drawings and are herein described indetail. It should be understood, however, that the drawings and detaileddescription thereto are not intended to be limiting to the particularform disclosed, but on the contrary, the intention is to cover allmodifications, equivalents and alternatives falling within the spiritand scope of the subject matter as defined by the appended claims.

DETAILED DESCRIPTION Acronyms

Various acronyms are used throughout the present application.Definitions of the most prominently used acronyms that may appearthroughout the present application are provided below:

UE: User Equipment

BS: Base Station

DL: Downlink (from BS to UE)

UL: Uplink (from UE to BS)

FDD: Frequency Division Duplexing

TDD: Time Division Duplexing

GSM: Global System for Mobile Communication

LTE: Long Term Evolution

TX: Transmission

RX: Reception

UMTS: Universal Mobile Telecommunication System

LAN: Local Area Network

WLAN: Wireless LAN

RAT: Radio Access Technology

TERMINOLOGY

The following is a glossary of terms used in this disclosure:

Memory Medium—Any of various types of non-transitory memory devices orstorage devices. The term “memory medium” is intended to include aninstallation medium, e.g., a CD-ROM, floppy disks, or tape device; acomputer system memory or random access memory such as DRAM, DDR RAM,SRAM, EDO RAM, Rambus RAM, etc.; a non-volatile memory such as a Flash,magnetic media, e.g., a hard drive, or optical storage; registers, orother similar types of memory elements, etc. The memory medium mayinclude other types of non-transitory memory as well or combinationsthereof. In addition, the memory medium may be located in a firstcomputer system in which the programs are executed, or may be located ina second different computer system which connects to the first computersystem over a network, such as the Internet. In the latter instance, thesecond computer system may provide program instructions to the firstcomputer for execution. The term “memory medium” may include two or morememory mediums which may reside in different locations, e.g., indifferent computer systems that are connected over a network. The memorymedium may store program instructions (e.g., embodied as computerprograms) that may be executed by one or more processors.

Carrier Medium—a memory medium as described above, as well as a physicaltransmission medium, such as a bus, network, and/or other physicaltransmission medium that conveys signals such as electrical,electromagnetic, or digital signals.

Programmable Hardware Element—includes various hardware devicescomprising multiple programmable function blocks connected via aprogrammable interconnect. Examples include FPGAs (Field ProgrammableGate Arrays), PLDs (Programmable Logic Devices), FPOAs (FieldProgrammable Object Arrays), and CPLDs (Complex PLDs). The programmablefunction blocks may range from fine grained (combinatorial logic or lookup tables) to coarse grained (arithmetic logic units or processorcores). A programmable hardware element may also be referred to as“reconfigurable logic”.

Computer System—any of various types of computing or processing systems,including a personal computer system (PC), mainframe computer system,workstation, network appliance, Internet appliance, personal digitalassistant (PDA), television system, grid computing system, or otherdevice or combinations of devices. In general, the term “computersystem” can be broadly defined to encompass any device (or combinationof devices) having at least one processor that executes instructionsfrom a memory medium.

User Equipment (UE) (or “UE Device”)—any of various types of computersystems devices which are mobile or portable and which performs wirelesscommunications. Examples of UE devices include mobile telephones orsmart phones (e.g., iPhone™, Android™-based phones), portable gamingdevices (e.g., Nintendo DS™, PlayStation Portable™, Gameboy Advance™,iPhone™), laptops, wearable devices (e.g. smart watch, smart glasses),PDAs, portable Internet devices, music players, data storage devices, orother handheld devices, etc. In general, the term “UE” or “UE device”may be broadly defined to encompass any electronic, computing, and/ortelecommunications device (or combination of devices) which is easilytransported by a user and capable of wireless communication.

Base Station—The term “Base Station” (also called “eNB”) has the fullbreadth of its ordinary meaning, and at least includes a wirelesscommunication station installed at a fixed location and used tocommunicate as part of a wireless telephone system or radio system.

Processing Element—refers to various elements or combinations ofelements that are capable of performing a function in a device, such asa user equipment or a cellular network device. Processing elements mayinclude, for example: processors and associated memory, portions orcircuits of individual processor cores, entire processor cores,processor arrays, circuits such as an ASIC (Application SpecificIntegrated Circuit), programmable hardware elements such as a fieldprogrammable gate array (FPGA), as well any of various combinations ofthe above.

Channel—a medium used to convey information from a sender (transmitter)to a receiver. It should be noted that since characteristics of the term“channel” may differ according to different wireless protocols, the term“channel” as used herein may be considered as being used in a mannerthat is consistent with the standard of the type of device withreference to which the term is used. In some standards, channel widthsmay be variable (e.g., depending on device capability, band conditions,etc.). For example, LTE may support scalable channel bandwidths from 1.4MHz to 20 MHz. In contrast, WLAN channels may be 22 MHz wide whileBluetooth channels may be 1 MHz wide. Other protocols and standards mayinclude different definitions of channels. Furthermore, some standardsmay define and use multiple types of channels, e.g., different channelsfor uplink or downlink and/or different channels for different uses suchas data, control information, etc.

Band—The term “band” has the full breadth of its ordinary meaning, andat least includes a section of spectrum (e.g., radio frequency spectrum)in which channels are used or set aside for the same purpose.

Automatically—refers to an action or operation performed by a computersystem (e.g., software executed by the computer system) or device (e.g.,circuitry, programmable hardware elements, ASICs, etc.), without userinput directly specifying or performing the action or operation. Thusthe term “automatically” is in contrast to an operation being manuallyperformed or specified by the user, where the user provides input todirectly perform the operation. An automatic procedure may be initiatedby input provided by the user, but the subsequent actions that areperformed “automatically” are not specified by the user, i.e., are notperformed “manually”, where the user specifies each action to perform.For example, a user filling out an electronic form by selecting eachfield and providing input specifying information (e.g., by typinginformation, selecting check boxes, radio selections, etc.) is fillingout the form manually, even though the computer system must update theform in response to the user actions. The form may be automaticallyfilled out by the computer system where the computer system (e.g.,software executing on the computer system) analyzes the fields of theform and fills in the form without any user input specifying the answersto the fields. As indicated above, the user may invoke the automaticfilling of the form, but is not involved in the actual filling of theform (e.g., the user is not manually specifying answers to fields butrather they are being automatically completed). The presentspecification provides various examples of operations beingautomatically performed in response to actions the user has taken.

Configured to—Various components may be described as “configured to”perform a task or tasks. In such contexts, “configured to” is a broadrecitation generally meaning “having structure that” performs the taskor tasks during operation. As such, the component can be configured toperform the task even when the component is not currently performingthat task (e.g., a set of electrical conductors may be configured toelectrically connect a module to another module, even when the twomodules are not connected). In some contexts, “configured to” may be abroad recitation of structure generally meaning “having circuitry that”performs the task or tasks during operation. As such, the component canbe configured to perform the task even when the component is notcurrently on. In general, the circuitry that forms the structurecorresponding to “configured to” may include hardware circuits.

Various components may be described as performing a task or tasks, forconvenience in the description. Such descriptions should be interpretedas including the phrase “configured to.” Reciting a component that isconfigured to perform one or more tasks is expressly intended not toinvoke 35 U.S.C. §112, paragraph six, interpretation for that component.

FIG. 1—Wireless Communication System

FIG. 1 illustrates a wireless cellular communication system, accordingto some embodiments. It is noted that FIG. 1 represents one possibilityamong many, and that features of the present disclosure may beimplemented in any of various systems, as desired.

As shown, the exemplary wireless communication system includes a basestation 102A which communicates over a transmission medium with one ormore wireless devices 106A, 106B, etc., through 106N. Wireless devicesmay be user devices, which may be referred to herein as “user equipment”(UE) or UE devices.

The base station 102 may be a base transceiver station (BTS) or cellsite, and may include hardware that enables wireless communication withthe UE devices 106A through 106N. The base station 102 may also beequipped to communicate with a network 100 (e.g., a core network of acellular service provider, a telecommunication network such as a publicswitched telephone network (PSTN), and/or the Internet, among variouspossibilities). Thus, the base station 102 may facilitate communicationbetween the UE devices 106 and/or between the UE devices 106 and thenetwork 100.

The communication area (or coverage area) of the base station 102 may bereferred to as a “cell.” The base station 102 and the UEs 106 may beconfigured to communicate over the transmission medium using any ofvarious radio access technologies (RATs) or wireless communicationtechnologies, such as GSM, UMTS (WCDMA, TDS-CDMA), LTE, LTE-Advanced(LTE-A), HSPA, 3GPP2 CDMA2000 (e.g., 1×RTT, 1×EV-DO, HRPD, eHRPD),Wi-Fi, WiMAX etc.

Base station 102 and other similar base stations (not shown) operatingaccording to one or more cellular communication technologies may thus beprovided as a network of cells, which may provide continuous or nearlycontinuous overlapping service to UE devices 106A-N and similar devicesover a wide geographic area via one or more cellular communicationtechnologies.

Thus, while base station 102 may presently represent a “serving cell”for wireless devices 106A-N as illustrated in FIG. 1, each UE device 106may also be capable of receiving signals from one or more other cells(e.g., cells provided by other base stations), which may be referred toas “neighboring cells”. Such cells may also be capable of facilitatingcommunication between user devices and/or between user devices and thenetwork 100.

Note that at least in some instances a UE device 106 may be capable ofcommunicating using multiple wireless communication technologies. Forexample, a UE device 106 might be configured to communicate using two ormore of GSM, UMTS, CDMA2000, WiMAX, LTE, LTE-A, WLAN, Bluetooth, one ormore global navigational satellite systems (GNSS, e.g., GPS or GLONASS),one and/or more mobile television broadcasting standards (e.g., ATSC-M/Hor DVB-H), etc. Other combinations of wireless communicationtechnologies (including more than two wireless communicationtechnologies) are also possible. Likewise, in some instances a UE device106 may be configured to communicate using only a single wirelesscommunication technology.

FIG. 2 illustrates UE device 106 (e.g., one of the devices 106A through106N) in communication with base station 102. The UE device 106 may havecellular communication capability, and as described above, may be adevice such as a mobile phone, a hand-held device, a media player, acomputer, a laptop or a tablet, or virtually any type of wirelessdevice.

The UE device 106 may include a processor that is configured to executeprogram instructions stored in memory. The UE device 106 may perform anyof the method embodiments described herein by executing such storedinstructions. Alternatively, or in addition, the UE device 106 mayinclude a programmable hardware element such as an FPGA(field-programmable gate array), or other circuitry, that is configuredto perform any of the method embodiments described herein, or anyportion of any of the method embodiments described herein.

In some embodiments, the UE device 106 may be configured to communicateusing any of multiple radio access technologies and/or wirelesscommunication protocols. For example, the UE device 106 may beconfigured to communicate using one or more of GSM, UMTS, CDMA2000, LTE,LTE-A, WLAN, Wi-Fi, WiMAX or GNSS. Other combinations of wirelesscommunication technologies are also possible.

The UE device 106 may include one or more antennas for communicatingusing one or more wireless communication protocols or technologies. Insome embodiments, the UE device 106 might be configured to communicateusing a single shared radio. The shared radio may couple to a singleantenna, or may couple to multiple antennas (e.g., for MIMO) forperforming wireless communications. Alternatively, the UE device 106 mayinclude two or more radios. For example, the UE 106 might include ashared radio for communicating using either of LTE or 1×RTT (or LTE orGSM), and separate radios for communicating using each of Wi-Fi andBluetooth. Other configurations are also possible.

FIG. 3—Example Block Diagram of a UE

FIG. 3 illustrates one possible block diagram of a UE 106. As shown, theUE 106 may include a system on chip (SOC) 300, which may includeportions for various purposes. For example, as shown, the SOC 300 mayinclude processor(s) 302 which may execute program instructions for theUE 106, and display circuitry 304 which may perform graphics processingand provide display signals to the display 360. The processor(s) 302 mayalso be coupled to memory management unit (MMU) 340, which may beconfigured to receive addresses from the processor(s) 302 and translatethose addresses to locations in memory (e.g., memory 306, read onlymemory (ROM) 350, NAND flash memory 310). The MMU 340 may be configuredto perform memory protection and page table translation or set up. Insome embodiments, the MMU 340 may be included as a portion of theprocessor(s) 302.

The UE 106 may also include other circuits or devices, such as thedisplay circuitry 304, radio 330, connector I/F 320, and/or display 360.

In the embodiment shown, ROM 350 may include a bootloader, which may beexecuted by the processor(s) 302 during boot up or initialization. Asalso shown, the SOC 300 may be coupled to various other circuits of theUE 106. For example, the UE 106 may include various types of memory(e.g., including NAND flash 310), a connector interface 320 (e.g., forcoupling to a computer system), the display 360, and wirelesscommunication circuitry (e.g., for communication using LTE, CDMA2000,Bluetooth, WiFi, GPS, etc.).

The UE device 106 may include at least one antenna, and in someembodiments multiple antennas, for performing wireless communicationwith base stations and/or other devices. For example, the UE device 106may use antenna 335 to perform the wireless communication. As notedabove, the UE may in some embodiments be configured to communicatewirelessly using a plurality of wireless communication standards.

As described herein, the UE 106 may include hardware and softwarecomponents for implementing a method for responding to enhanced pagingaccording to embodiments of this disclosure.

The processor 302 of the UE device 106 may be configured to implementpart or all of the methods described herein, e.g., by executing programinstructions stored on a memory medium (e.g., a non-transitorycomputer-readable memory medium). In other embodiments, processor 302may be configured as a programmable hardware element, such as an FPGA(Field Programmable Gate Array), or as an ASIC (Application SpecificIntegrated Circuit). Alternatively (or in addition) the processor 302 ofthe UE 106, in conjunction with one or more of the other components 300,304, 306, 310, 320, 330, 340, 350, 360 may be configured to implementpart or all of the features described herein.

In addition, as described herein, processor 302 may be comprised of oneor more processing elements. In other words, one or more processingelements may be included in processor 302. Thus, processor 302 mayinclude one or more integrated circuits (ICs) that are configured toperform the functions of processor 302. In addition, each integratedcircuit may include circuitry (e.g., first circuitry, second circuitry,etc.) configured to perform the functions of processor 302.

Further, as described herein, radio 330 may be comprised of one or moreprocessing elements. In other words, one or more processing elements maybe included in radio 330. Thus, radio 330 may include one or moreintegrated circuits (ICs) that are configured to perform the functionsof radio 330. In addition, each integrated circuit may include circuitry(e.g., first circuitry, second circuitry, etc.) configured to performthe functions of radio 330.

FIG. 4—Base Station

FIG. 4 illustrates a base station 102, according to some embodiments. Itis noted that the base station of FIG. 4 is merely one example of apossible base station. As shown, the base station 102 may includeprocessor(s) 404 which may execute program instructions for the basestation 102. The processor(s) 404 may also be coupled to memorymanagement unit (MMU) 440, which may be configured to receive addressesfrom the processor(s) 404 and translate those addresses to locations inmemory (e.g., memory 460 and read only memory (ROM) 450) or to othercircuits or devices.

The base station 102 may include at least one network port 470. Thenetwork port 470 may be configured to couple to a telephone network andprovide a plurality of devices, such as UE devices 106, access to thetelephone network as described above.

The network port 470 (or an additional network port) may also oralternatively be configured to couple to a cellular network, e.g., acore network of a cellular service provider. The core network mayprovide mobility related services and/or other services to a pluralityof devices, such as UE devices 106. In some cases, the network port 470may couple to a telephone network via the core network, and/or the corenetwork may provide a telephone network (e.g., among other UE devicesserviced by the cellular service provider).

The base station 102 may include a radio 430, a communication chain 432and at least one antenna 434. The base station may be configured tooperate as a wireless transceiver and may be further configured tocommunicate with UE devices 106 via radio 430, communication chain 432and the at least one antenna 434. Communication chain 432 may be areceive chain, a transmit chain or both. The radio 430 may be configuredto communicate via various RATs, including, but not limited to, GSM,UMTS, LTE, WCDMA, CDMA2000, WiMAX, etc.

The processor(s) 404 of the base station 102 may be configured toimplement part or all of the methods described herein, e.g., byexecuting program instructions stored on a memory medium (e.g., anon-transitory computer-readable memory medium). Alternatively, theprocessor 404 may be configured as a programmable hardware element, suchas an FPGA (Field Programmable Gate Array), or as an ASIC (ApplicationSpecific Integrated Circuit), or a combination thereof. Alternatively(or in addition) processor(s) 404 of the base station 102, inconjunction with one or more of the other components 430, 440, 450, 460,and 470 may be configured to implement part or all of the featuresdescribed herein.

In addition, as described herein, processor(s) 404 may be comprised ofone or more processing elements. In other words, one or more processingelements may be included in processor(s) 404. Thus, processor(s) 404 mayinclude one or more integrated circuits (ICs) that are configured toperform the functions of processor(s) 404. In addition, each integratedcircuit may include circuitry (e.g., first circuitry, second circuitry,etc.) configured to perform the functions of processor(s) 404.

Further, as described herein, radio 430 may be comprised of one or moreprocessing elements. In other words, one or more processing elements maybe included in radio 430. Thus, radio 430 may include one or moreintegrated circuits (ICs) that are configured to perform the functionsof radio 430. In addition, each integrated circuit may include circuitry(e.g., first circuitry, second circuitry, etc.) configured to performthe functions of radio 430.

Channels in LTE

LTE uses various channels so that data can be transported across the LTEradio interface. These channels are used to segregate the differenttypes of data and allow them to be transported across the radio accessnetwork in an orderly fashion. The different channels effectivelyprovide interfaces to the higher layers within the LTE protocolstructure, and enable an orderly and defined segregation of the data.

There are three categories or types of LTE data channels as follows.

Physical channels: These are transmission channels that carry user dataand control messages.

Transport channels: The physical layer transport channels offerinformation transfer to Medium Access Control (MAC) and higher layers.

Logical channels: Provide services for the Medium Access Control (MAC)layer within the LTE protocol structure.

LTE defines a number of physical downlink channels to carry informationfrom the base station to the UE. The LTE downlink comprises a physicaldownlink shared channel (PDSCH), a physical downlink control channel(PDCCH), and a physical hybrid automatic repeat request (HARM) indicatorchannel (PHICH). The PDSCH is the downlink channel that carries all userdata and all signaling messages. The PDSCH is the main data bearingchannel which is allocated to users on a dynamic and opportunisticbasis. The PDCCH carries the layer one control for the shared channel.Thus, the PDSCH is the key channel for communicating information to theUE, and the PDCCH communicates metadata for the information, e.g., “who”the data is for, “what” data is sent, and “how” the data is sent overthe air in the PDSCH. Further, the PHICH is the downlink channel thatcarries HARQ acknowledgments (ACK/NACK) for uplink data transfers.

LTE also defines a number of physical uplink channels to carryinformation from the UE to the base station. The LTE uplink comprises aphysical uplink shared channel (PUSCH) and a physical uplink controlchannel (PUCCH). The PUSCH is the uplink counterpart to the PDSCH. ThePUCCH provides the various control signaling requirements for uplinkcommunications including carrying the channel quality indicator (CQI),the rank indicator (RI), and the pre-coding matrix indicator (PMI), aswell as, HARQ acknowledgments (ACK/NACK).

As described above, in LTE the base station (eNB) assigns UL resourcesusing the PDCCH, wherein this assignment of resources is called a ULgrant. The UL grant may be a type of persistent UL grant such as asemi-persistent scheduling (SPS) UL grant. The persistent orsemi-persistent UL grant may be configured by radio resource control(RRC) layer signaling and the UE may be configured with SPS by the basestation, and then the base station may activate the UE to use SPS.Persistent or semi-persistent UL grants, such as SPS, allows for apersistent, periodic UL grant. Thus, the UE may transmit new informationperiodically without receiving a new UL grant for each transmission.Alternatively, the UL grant may be for a specified amount ofinformation, and the base station may send additional UL grants based onscheduling requests from the UE.

TTI Bundling

In normal operations, a transport block is converted to multipleredundancy versions after coding and the first redundancy version issent in a sub-frame. If this first redundancy version is not properlyreceived, the receiver will return a negative acknowledge (NACK), whichresults in a hybrid automatic repeat request (HARQ), i.e., aretransmission of a new, typically different, redundancy version. Onecommon type of automatic repeat request is HARQ (hybrid automatic repeatrequest). The HARQ ACK/NACK is sent 4 sub-frame durations or more afterthe first transmission. Thus in normal operations subsequenttransmissions of the transport block, i.e., subsequent transmissions ofanother redundancy version, are dependent on non-receipt (NACK) of thefirst redundancy version that was transmitted.

TTI bundling is a technique used to send a transport block multipletimes in consecutive sub-frames without waiting for HARQ ACK/NACKmessages. In TTI bundling, a plurality of the redundancy versions canall be sent in consecutive (adjacent) sub-frames without waiting for theHARQ ACK/NACK feedback. In addition, a combined ACK/NACK can be sentafter processing all the transmissions of a transport block, i.e., afterall of the consecutive redundancy versions have been sent. Onemotivation for TTI bundling is the low transmission power of somehandsets, short TTI length. TTI bundling is designed to improve the ULcoverage of applications like VOIP over LTE wherein low power handsetsare likely to be involved.

Thus, TTI bundling is used to achieve successful transmissions frompower limited UEs and range limited UEs. The TTI bundling process, forthese new types of devices might be triggered by the UE informing thebase station about its current power limitations via radio resourcecontrol (RRC) layer signaling. For example, this situation may arise atthe edge of a cell when the UE is required to transmit at high power,but where the UE has limited power capability. After the base station isnotified about the UE's limited power capability, the UE may transmitthe various redundancy versions of the same transport block inconsecutive sub-frames or TTIs to the base station, giving rise to thename TTI bundling. These multiple consecutive transmissions may providefor reduced overhead. A single HARQ ACK/NACK for the combinedtransmissions is generated by the base station after processing the TTIbundle. The transmission of a TTI bundle, instead of merely a singleredundancy version transmission, may reduce the error rate of thetransport block. This approach can also reduce the delay in the HARQprocess compared to transmissions of the redundancy versions separatedin time using the normal (non-TTI bundling) approach.

FIG. 5A illustrates an example of TTI bundling, i.e., contiguousretransmissions of different redundancy versions of an UL packet. Asshown, the UE transmits four different redundancy versions of the dataconsecutively, these being redundancy versions (RVs) 0, 3, 2 and 1. Thebase station will send an ACK/NACK feedback after the fourthretransmission, as shown.

LTE Uplink HARQ Procedure

In normal LTE operations, the uplink (UL) procedure may proceed asillustrated in FIG. 5B. A UE (e.g., UE 106) may receive a new uplinkgrant at 502 on the PDCCH. At 504, 4 sub-frames after receiving thegrant, the UE may send data on the PUSCH using redundancy version 0(RV0). At 506, the UE may receive a NACK on the PHICH 4 sub-frames aftersending RV0. In response, at 508, the UE may send RV1 4 sub-frames afterreceiving the NACK. The procedure continues with the 4 sub-frame spacingat 510 with the UE receiving another NACK from the base station. Afteranother 4 sub-frames, the UE sends RV2 at 512 and receives an ACK on thePHICH at 514 4 sub-frames after sending RV2. In addition, at 514, the UEreceives a new grant. The procedure is then repeated with the new grantuntil the UE receives a NACK. However, a peak current limited devicesthat may have a reduced duty cycle (e.g., 1 transmission every 8sub-frames) may not be able to maintain the LTE uplink timeline. Hence,a mechanism is needed to enable UL transmissions in such scenarios andto make sure that the UE may still transmit in the UL without violatingthe UL timeline,

FIG. 6: HARQ Timeline

FIG. 6 illustrates an exemplary timeline of a HARQ process, according tosome embodiments. As discussed above, a peak current limited device(i.e., a device that has limited battery and/or limited power amplifiercapability), such as UE 106, may be unable to transmit continuously inthe uplink. In other words, the peak current limited device may operateon a low duty cycle such as 1 transmission (TX) every 8 milliseconds(ms) in a frequency division duplexing (FDD) system and/or 1 TX every 10ms in a time division duplexing (TDD) system.

In the embodiment illustrated in FIG. 6, transmission of HARQ ACK/NACKon the PUCCH may be aligned with data transmitted on the PUSCH. Thus, asshown, base station 102 (i.e., eNB 102) may transmit data on the PDSCHin sub-frame 601 and UE 106 may receive the data in sub-frame 602. Foursub-frames after receiving the data on the PDSCH the UE may transmitboth user data and HARQ ACK/NACK on the PUSCH in sub-frame 604. In otherwords, the data and control information may be multiplexed on the PUSCH.

Note that in some embodiments, the base station may limit the number ofHARQ processes to one in both uplink and downlink. Limiting the HARQprocesses to one may allow the peak current limited device to maintainthe uplink timeline, which in this instance (e.g., for an FDD system)may be one transmission every eight sub-frames. Note that for a TDDsystem, the peak current limited device may maintain the uplink timelinefor a single HARQ process by transmitting once every ten sub-frames. Oneexample would be to use type 2 sub-frame configuration 5 as defined by3GPP TS 36.211. Further, in some embodiments, the base station mayoffset downlink and uplink HARQ processes by four sub-frames such thatPUSCH and PUCCH may be aligned. Consequently, in the downlink, the PHICHand PDSCH may be aligned as well.

Returning to FIG. 6, after sending the user data and HARQ ACK/NACK insub-frame 604, the UE may not transmit again for the next sevensub-frames (i.e., the next UE transmission may occur at sub-frame 608).However, in the fourth sub-frame after transmission (sub-frame 606), theUE may receive data on the PDSCH and HARQ ACK/NACK on the PHICH sentfrom the base station at sub-frame 605. Then, at the eighth sub-frameafter the prior transmission (i.e., sub-frame 608), the UE may transmituser data and HARQ ACK/NACK on the PUSCH to the base station and thebase station may receive the user data and the HARQ ACK/NACK atsub-frame 607. In certain embodiments, such a timeline may allow the UEto conserve transmission power while maintaining the HARQ processtimeline.

In some embodiments for a TDD system, after sending the user data andHARQ ACK/NACK, the UE may not transmit again for the next ninesub-frames. However, in the fifth sub-frame after transmission, the UEmay receive data on the PDSCH and HARQ ACK/NACK on the PHICH. Then, atthe tenth sub-frame after the prior transmission, the UE may transmituser data and HARQ ACK/NACK on the PUSCH.

FIGS. 7-8: Improved Downlink Budget Timeline

FIG. 7 illustrates an exemplary timeline for improving the downlinkbudget, according to some embodiments. As shown in FIG. 7, in order toimprove the link budget, downlink transmit time interval bundling(TTI-B) as described above may be used without compromising the low dutycycle of a peak current limited device. Note that in some embodiments,the peak current limited device may not support full duplex FDD and maystill maintain the low duty cycle.

As shown, the base station (i.e., eNB 102) may transmit data on thePDSCH in sub-frame 601 and the UE (i.e., UE 106) may receive the data insub-frame 602. As described above with reference to FIG. 6, in order tomaintain the uplink timeline, the UE may transmit HARQ ACK/NACK and userdata on the PUSCH four sub-frames (i.e., sub-frame 604) after receivingdata on the PDSCH sent from the base station at sub-frame 603.Additionally, the UE may then receive data in the next four sub-frames(sub-frames 606 a-606 d) sent from the base station in consecutivesub-frames 605 a-605 d. As shown, in the three sub-frames aftertransmission (i.e., sub-frames 606 a-606 c), the UE may receiveredundancy versions of the data according to TTI-B on the PDSCH.However, in the fourth sub-frame after transmission (i.e., sub-frame 606d), the UE may receive both a redundancy version of the data on thePDSCH and HARQ ACK/NACK on the PHICH as shown in order to maintain theHARQ process timeline. Then, the UE may transmit user data and HARQACK/NACK four sub-frames later (i.e., sub-frame 608) according to theHARQ process timeline and the base station may receive the user data andthe HARQ ACK/NACK at sub-frame 607.

FIG. 8 illustrates another exemplary timeline for improving the downlinkbudget, according to some embodiments. As shown in FIG. 8, multipledownlink HARQ processes (i.e., Tx_i-2, Tx_i-1, Tx_i) may be used withoutcompromising the low duty cycle of a peak current limited device. Notethat in some embodiments, the peak current limited device may notsupport full duplex FDD and may still maintain the low duty cycle.

As shown, the base station (i.e., eNB 102) may transmit data on thePDSCH in sub-frame 601 and the UE (i.e., UE 106) may receive the data insub-frame 602. In order to maintain the uplink timeline, the UE maytransmit user data on the PUSCH as well as HARQ ACK/NACK in the fourthsub-frame (sub-frame 604) after receiving data from the base stationsent in sub-frame 603. In order to support multiple downlink HARQprocesses, the UE may receive data (Tx_i-2, Tx-i-1, and Tx_i) from thebase station (sent in sub-frames 605 d-605 f) in the second, third, andfourth sub-frames (i.e., sub-frames 606 d-606 f) after transmission.Note that in some embodiments the UE may not be able to transmit data inthe first sub-frame after receiving data because of propagation delay.In other words, the UE may not be able to fully decode the downlink(received) transmission within the duration of the sub-frame; hence, theUE may not be ready to transmit in the next sub-frame. Thus, in someembodiments, in order to maintain the uplink timeline, an uplinktransmission may not be preceded by a downlink transmission (in theimmediately preceding sub-frame). However, it is contemplated that insome embodiments, the uplink transmission may be preceded by a downlinktransmission in the immediately preceding sub-frame. Additionally, andsimilar to the embodiments described in FIGS. 6 and 7, the UE may alsoreceive HARQ ACK/NACK on the PHICH in the fourth sub-frame (sub-frame6060. The UE may then wait three sub-frames (eight sub-frames after lasttransmission) before transmitting user data on the PUSCH in sub-frame608 that may be received by the base station in sub-frame 607.

In some embodiments, the UE may additionally send HARQ ACK/NACK for eachHARQ process on the payload of the PUSCH at sub-frame 608.Alternatively, or in addition to, the UE may combine the HARQ ACK/NACKfor each HARQ process into a single ACK/NACK carried on the PUSCH andsent at sub-frame 608. In such embodiments, the UE may send an ACK onlywhen each HARQ process is successfully received and may otherwise send aNACK if any of the HARQ processes is not successfully received. Thus, insuch instances, the UE may transmit a NACK if any one of the HARQprocesses fails, and, in response, the base station may retransmit allthe HARQ processes.

FIGS. 9-11: Multiple Uplink HARQ Processes

FIGS. 9, 10 and 11 illustrate exemplary timelines for multiple uplinkHARQ processes, according to some embodiments. As shown in FIG. 9, ininstances when the peak current limited device may have enough power totransmit more than once per duty cycle (e.g., under improved channelconditions such that the power requirements for transmitting arereduced), multiple downlink HARQ processes may be used (i.e., HARQ_1 andHARQ_2). Alternatively, uplink distributed TTI bundling may be used asdescribed below in reference to FIGS. 14 and 15. Note that in someembodiments, the peak current limited device may not be able tosimultaneously transmit and receive. In other words, the peak currentlimited device may still be constrained to half duplex. Further, in someembodiments, to keep the uplink timeline of all UEs that may be incommunication with the base station, an uplink transmission may not bepreceded by a downlink transmission without a sub-frame in betweenbecause the UE may not be able to fully decode a downlink transmissionthat is preceding an uplink transmission due to propagation delay. Notethat it is contemplated that in some embodiments, the uplinktransmission may be preceded by a downlink transmission in theimmediately preceding sub-frame without compromising the uplinktimeline.

As shown in FIG. 9, the base station (i.e., eNB 102) may transmit dataon the PDSCH in sub-frame 601 and the UE (i.e., UE 106) may receive thedata in sub-frame 602. In order to maintain the uplink timeline, the UEmay transmit user data on the PUSCH as well as HARQ ACK/NACK in thefourth sub-frame (sub-frame 604) after receiving data from the basestation sent at sub-frame 603. Note that this receive/transmit pair(sub-frame 602, 604, 606, and 608 on the UE side and sub-frame 601, 603,605, and 607 on the base station side) may be associated with both afirst uplink HARQ process and a first downlink HARQ process (i.e.,HARQ_DL_1 and HARQ_UL_1). In addition, the UE may have a second uplinkHARQ process (HARQ_UL_2) and may transmit user data associated with thesecond HARQ process via another transmit/receive pair (sub-frame 614,616, and 618 on the UE side and sub-frame 613, 615, and 617 on the basestation side). Thus, the UE may transmit user data on the PUSCH as wellas HARQ ACK/NACK (associated with HARQ_DL_2) in the second sub-frame(i.e., sub-frame 614) after receiving data from the base stationassociated with HARQ_DL_1 at sub-frame 602. In this manner, the UE maymaintain the same duty cycle for each HARQ process. In other words, theUE maintains the HARQ timeline of one transmission every eightsub-frames for each HARQ process.

Note that in an embodiment supporting TDD, the UE may support two uplinkHARQ processes with a HARQ timeline of one transmission every fivesub-frames in accordance with the HARQ timeline for TDD.

In some embodiments, the number of downlink and uplink processes may beequivalent. In other words, the HARQ processes may be symmetric in someembodiments. However, it is envisioned, as further described below, thatin some embodiments, the HARQ processes may be asymmetric (e.g., thenumber of downlink HARQ processes is not equivalent to the number ofuplink HARQ processes). Thus, for example, as shown in FIG. 9, there maybe two downlink HARQ processes and two uplink HARQ processes. In certainembodiments, the uplink HARQ processes may be limited to two. In someembodiments, this may be due to battery and/or power constraints.

FIG. 10 illustrates an exemplary HARQ timeline supporting multipleuplink HARQ processes and downlink TTI bundling. As shown, the basestation (i.e., eNB 102) may send a first TTI bundle (Tx0 and Tx1) for afirst downlink HARQ process (HARQ_DL_1) at sub-frames 901 a and 901 band the UE (i.e., UE 106) may receive the first transmission of the TTIbundle (Tx0) at sub-frame 902 a on the PDSCH. Additionally, the UE mayreceive the second transmission of the TTI bundle (Tx1) at sub-frame 902b on the PDSCH. As discussed above, a TTI bundle may include multipleredundancy versions of the same data. Thus, in this instance, Tx0 andTx1 may be the same data encoded with differing versions of redundancy.

In addition, the PDSCH may include an ACK/NACK (A/N) from a previoustransmission from the UE. In certain embodiments the ACK/NACK may besent on the PHICH as described above. In some embodiments, the ACK/NACKmay be an aggregated ACK/NACK as described above.

At sub-frames 903 a and 903 b, the base station may send a second set ofTTI bundled transmissions and the UE may receive the transmissions onthe PDSCH at sub-frames 904 a and 904 b. As with the first set of TTIbundled transmissions, the UE may receive ACK/NACK included in the PDSCHfrom a previous transmission at sub-frame 904 b.

The first HARQ process (HARQ_DL_1) may continue at sub-frame 906 (4sub-frames after receipt of the second transmission of the TTI bundleassociated with HARQ_1) and the UE may transmit user data (associatedwith HARQ_UL_1) and ACK/NACK (A/N) (associated with HARQ_DL_1) on thePUSCH which may be received by the base station at sub-frame 907.

Similarly, the second HARQ process (HARQ_DL_2) may continue at sub-frame908 and the UE may transmit user data (associated with HARQ_UL_2) andA/N (associated with HARQ_DL_2) on the PUSCH which may be received bythe base station at sub-frame 909.

At sub-frames 911 a and 911 b, and similarly, at sub-frames 913 a and913 b, the base station may send TTI bundled transmissions and the UEmay receive the transmissions on the PDSCH at sub-frames 912 a and 912b, and similarly, sub-frames 914 a and 914 b. Note that the UE mayreceive an ACK/NACK associated with HARQ_UL_1 at sub-frame 912 b and anACK/NACK associated with HARQ_UL_2 at sub-frame 914 b. The ACK/ANCKs maybe included in the PDSCH. The communications may continue as shown. TheUE may transmit additional user data and ACK/NACK associated withHARQ_DL_1 and HARQ_DL_2 at sub-frames 916 and 918 which may be receivedby the base station at sub-frames 917 and 919, respectively.

FIG. 11 illustrates an exemplary HARQ timeline supporting multipleuplink and downlink HARQ processes. As noted above, the uplink anddownlink HARQ processes may be symmetric (i.e., equivalent in number) orasymmetric (i.e., not equivalent in number). In some embodiments, theuplink and downlink HARQ processes may be asymmetric because the UE ispeak current and/or link budget limited. In other words, the UE may nothave enough power to perform transmissions for more than one or two ULHARQ processes.

As shown, a UE (UE 106) may support four downlink HARQ processes(HARQ_DL_1-HARQ_DL_4) and two uplink HARQ processes (HARQ_UL_1 andHARQ_UL_2). Thus, in some embodiments, the UE may transmit or receive ineach sub-frame. For example, the base station (eNB 102) may transmitdata on the PDSCH at sub-frames 1101, 1103, 1105, and 1107 and the UEmay receive the data at sub-frames 1102, 1104, 1106, and 1108,respectively.

As illustrated, the UE may transmit ACK/NACK information on the PUCCH atsub-frames 1121 (received at sub-frame 1122) and 1125 (received atsub-frame 1126). In some embodiments, the UE may support format 1a forthe PUCCH while in other embodiments the UE may additionally supportformat 3 for the PUCCH. Note that format 1a includes on 1 bit forACK/NACK whereas format 3 may support up to 10 bits for ACK/NACK.Additionally, the UE may transmit user data and ACK/NACK on the PUSCH atsub-frames 1123 (received at sub-frame 1124) and 1125 (received atsub-frame 1126). In other words, the UE may alternate transmitting onthe PUSCH and PUCCH depending on whether or not the UE has data to send.Thus, when the UE has data to send, the ACK/NACK may be included in thepayload of the PUSCH. Additionally, in some embodiments, the powerrequired to transmit on the PUCCH may be lower than the power requiredto transmit on the PUSCH. Therefore, the UE may conserve power in someembodiments by transmitting on the PUSCH. Note that, in accordance withthe HARQ timeline, respective ACK/NACKs for a HARQ process (uplink ordownlink) may be sent four sub-frames after receipt of data associatedwith the HARQ process.

The signaling may be repeated for a second set of sub-frames as shown.Thus, the base station may transmit data at sub-frames 1111, 1113, 1115,and 1117 (respectively received at the UE in sub-frames 1112, 1114,1116, and 1118). Note that the base station may include the ACK/NACKsassociated with HARQ_UL_1 and HARQ_UL_2 on the PDSCH at sub-frames 1113and 1117 in accordance with the HARQ timeline. Similarly, the UE maytransmit ACK/NACKs on the PUCCH at sub-frames 1131 and 1135 (received bythe base station at sub-frames 1132 and 1136, respectively). Further,the UE may transmit user data and ACK/NACKs on the PUSCH at sub-frames1133 (received by the base station at sub-frame 1134) and 1137 (receivedby the base station at sub-frame 1138).

FIGS. 12-13: Methods for HARQ Signaling

FIGS. 12 and 13 illustrate methods for HARQ signaling according toembodiments. The methods may include the signaling operations between abase station, such as eNB 102, and a user equipment, such as UE 106,shown in FIGS. 12 and 13. Note that the methods may also include anysubset of the features, elements and embodiments described above. Thus,in some embodiments the UE may be a peak current limited device and insome embodiments, the UE may have a transmit duty cycle of X sub-frames.

Turning to FIG. 12, at 1210 the UE may receive first data from the basestation. The first data may be received on the PDSCH as described in theabove Figures.

At 1220, the UE may send first user data and a first ACK/NACK Ysub-frames after receiving the first data from the base station. In someembodiments, X may be two times Y. Further, in some embodiments, Y maybe four sub-frames and X may be eight sub-frames. In such embodiments,the UE may be configured to transmit using frequency division duplexing(FDD). Additionally, in some embodiments, Y may be five sub-frames and Xmay be ten sub-frames and the UE may be configured to transmit usingtime division duplexing (TDD).

In some embodiments, X may be the sum of Y and Z, where Y is a number ofsub-frames between the UE receiving and transmitting and Z is a numberof sub-frames between the UE transmitting and receiving. In suchembodiments, Y and Z may not be equal.

At 1230, the UE may receive second data from the base station on thePDSCH and, at 1240, the UE may send second user data and a secondACK/NACK Y sub-frames after receiving the second data from the basestation and X sub-frames after transmitting the first data at 1220.

In certain embodiments, the first and second user data may betransmitted on the PUSCH and the first and second ACK/NACKs may betransmitted on the PUSCH. In such embodiments, the PUSCH and the PUCCHmay be aligned.

In some embodiments, the first data may include first information andthe second data may include second information and a third ACK/NACK thatmay correspond to the first user data. In such embodiments the secondinformation may be received on the PDSCH and the third ACK/NACK may bereceived on the PHICH and the PDSCH and PHICH may be aligned.Additionally, the PUSCH and PHICH may be offset by X sub-frames.

In some embodiments, the UE may be configured to receive up to Y−1redundancy versions of the first data in consecutive sub-frames prior toreceiving the first data and Y−1 redundancy versions of the second datain consecutive sub-frames prior to receiving the second data. Forexample, if X is eight sub-frames and Y is four sub-frames, then the UEmay be configured to receive up to three redundancy versions of thefirst/second data in three consecutive sub-frames prior to receiving thefirst/second data. Note that the first/second data may itself be adifferent redundancy version that the prior redundancy versions. Thus,the UE may receive up to Y redundancy versions of first/second data insome embodiments.

In one embodiment, the UE may be configured to receive up to Y−1additional data in consecutive sub-frames prior to receiving the firstdata and Y−1 additional data in consecutive sub-frames prior toreceiving the second data. In other words, the UE may support more than1 downlink HARQ process in certain embodiments. For example, if X iseight sub-frames and Y is four sub-frames, then the UE may be configuredto receive up to three additional data (each data being associated witha different downlink HARQ process) in 3 consecutive sub-frames prior toreceiving the first/second data. Note that the first/second data may beassociated with a downlink HARQ process. Thus, the UE may support up toY downlink HARQ processes in some embodiments.

In embodiments in which multiple downlink HARQ processes may besupported, the first/second data may include the first/second ACK/NACKas well as respective ACK/NACKs for each additional downlink HARQprocess. Thus, in some embodiments, the ACK/NACK for the HARQ processesmay be included in the payload of the PUSCH.

Alternatively, in embodiments in which multiple downlink HARQ processesmay be supported, the first/second ACK/NACK may serve as an ACK/NACK forall the downlink HARQ processes. In other words, the ACK/NACK for allthe downlink HARQ processes may be aggregated into a single ACK/NACKsent on the PUCCH. In some embodiments, the ACK/NACKs for all thedownlink HARQ processes may be NAND together such that if any of thedownlink HARQ processes result in a NACK, then the UE may send a NACKand the base station may retransmit all HARQ processes. Alternatively,if all HARQ processes were received successfully, the UE may send asingle ACK.

In certain embodiments, the transmit duty cycle of the UE may correspondto a single uplink HARQ process. In such embodiments, the UE may beconfigured to support multiple uplink HARQ processes. Thus, in someembodiments, the first and second user data may correspond to a firstuplink HARQ process and the UE may be further configured to transmitthird user data and a third ACK/NACK in a third sub-frame subsequent toreceiving third data from the base station X sub-frames prior. The thirdACK/NACK may correspond to the third data and the third sub-frame may betwo sub-frames after the first sub-frame. Further, the UE may beconfigured to transmit fourth user data and a fourth ACK/NACK in afourth sub-frame subsequent to receiving fourth data from the basestation X sub-frames prior, The fourth ACK/NACK may correspond to thefourth data and the fourth sub-frame may be X sub-frames after the thirdsub-frame.

Now, turning to FIG. 13, at 1310 a UE (i.e., UE 106) may communicate toa base station (i.e., eNB 102) a number of uplink (UL) HARQ processessupported by the UE. In some embodiments, the UE may send a message thatincludes the number of UL HARQ processes supported to the base station.The message may be sent via a medium access control (MAC) layer controlelement (CE).

In some embodiments, the UE may determine the number of UL HARQprocesses supported using at least one metric and send the number of ULHARQ processes supported to the base station. Thus, in some embodiments,the UE may determine available power headroom and compare the availablepower headroom to a first threshold. If the available power headroom isless than the first threshold, the UE may only support one UL HARQprocess. However, if the available power headroom is greater than asecond threshold, the UE may support two UL HARQ processes.

Note that in certain embodiments, the UE may report to the base stationits power headroom and the base station may determine the number of ULHARQ processes supported by the UE based on the power headroom. In otherwords, the base station may implicitly determine the number of UL HARQprocesses support without any explicit signaling from the UE.

In another embodiment, the at least one metric may include one or moreof UL block error ratio (BLER) and UL signal to interference plus noiseratio (SINR). Further, the UE may compare one or more of the at leastone metric to a threshold to determine the number of UL HARQ processessupported.

In some embodiments, the number of UL HARQ processes may be equal to thenumber of DL HARQ processes. In other words, the UL and DL HARQprocesses may be symmetric. In some embodiments, the base station maynot support ACK/NACK bundling as described above, thus the number of DLprocesses may be linked to the number of UL processes, i.e., the basestation may constrain the UL and DL HARQ processes to be symmetric innumber. Note that in such embodiments, the channel conditions may besuch that the UE's power may not be limited.

In other embodiments, the number of UL HARQ processes may not be equalto the number of DL HARQ processes. In other words, the UL and DL HARQprocesses may be asymmetric. In such embodiments, the UE may be powerconstrained (e.g., peak current limited) and/or link budget limited.Therefore, as further discussed below, the UE may transmit ACK/NACKs onboth the PUSCH and the PUCCH in order to conserve power. Alternatively,or in addition, in some embodiments the UL and DL HARQ processes may beasymmetric in number and the UE may utilize any of ACK/NACK bundling,PUCCH format 3, or multiple ACK/NACKs in the PUSCH as described above.

At 1320, the UE may receive first information from the base station. Thefirst information may be received in at least a first sub-frame.Additionally, the first information may correspond to at least a firstdownlink (DL) HARQ process and a number of DL HARQ processes may dependupon the number of UL HARQ processes. Further, in some embodiments, thenumber of DL HARQ processes may also depend upon the DL channelconditions. Thus, if channel conditions are below a first threshold, thefirst information may include a plurality of redundancy versions offirst data and the UE may receive the plurality of redundancy version inconsecutive sub-frames. In such embodiments, the first data may beassociated with the first DL HARQ process. Further, in some embodiments,the UE may have a transmit duty cycle of X sub-frames and may supportonly one DL HARQ process and one UL HARQ process. Thus, the base stationmay send a TTI bundle for the DL HARQ process and the UE, X sub-frameslater, may send user data and an ACK/NACK on the PUSCH as describedabove.

In addition, if channel conditions are above the first threshold, thefirst information may include a plurality of DL HARQ processes and theUE may receive the plurality of DL HARQ processes in consecutivesub-frames.

At 1330, the UE may send second information to the base station Xsub-frames after the first sub-frame. The second information may includea first ACK/NACK associated with the first DL HARQ process.Additionally, in some embodiments, the UE may support format 1a andformat 3 for sending ACK/NACKs on the PUCCH.

In embodiments including multiple DL HARQ processes, the UE may send anACK/NACK corresponding to each DL HARQ process and each correspondingACK/NACK may be sent X sub-frames after a sub-frame in which each DLHARQ process was received. Thus, in some embodiments, the UE may includea first ACK/NACK for at least one of the plurality of DL HARQ processeson a payload of second data associated with a first UL HARQ process. Thesecond data and the first ACK/NACK may be sent on a physical uplinkshared channel (PUSCH). In addition, the UE may send a second ACK/NACKfor at least one other of the plurality of DL HARQ processes on aphysical uplink control channel (PUCCH) using format 1a or format 3.Note that in some embodiments, a power to transmit on the PUCCH may belower than a power to transmit on the PUSCH.

FIG. 14: HARQ Timeline for VoLTE

FIG. 14 illustrates an exemplary timeline for TTI bundling and connecteddiscontinuous reception cycle (C-DRX), according to some embodiments. InVoLTE (Voice over LTE), a C-DRX cycle of 40 milliseconds is used to makesure that the packet delay budget is obtained. Further, a device that islink budget limited may need to use TTI bundling as described above inreference to FIG. 5A to achieve successful decoding at the base station.However, a peak current limited device may not be able to performstandard TTI bundling since it may not be able to transmit in more thantwo consecutive sub-frames as required by standard TTI bundling, thusimprovements in the field are needed.

Turning to FIG. 14, an exemplary timeline for a C-DRX cycle of 40milliseconds with distributed TTI bundling is illustrated. As shown, theUE (i.e., UE 106) may receive an uplink grant on PDCCH at sub-frame 0.At sub-frame 4, the UE may send the first of two consecutivetransmissions of user data. The transmissions may be sent usingdifferent redundancy versions as assigned by the base station (i.e.,base station 102). Four sub-frames after the second transmission (i.e.,sub-frame 9) the UE may receive a NACK on the PHICH. Note that inbetween the transmission at sub-frame 5 and the receive at sub-frame 9,the UE may be inactive. Then, at sub-frame 13, the UE may again send twoconsecutive transmissions. Thus, the UE may transmit 2 times in 9sub-frames. The UE may then receive another NACK at sub-frame 18 andcontinue the procedure until the end of the C-DRX cycle at sub-frame 40.Thus, the UE may have transmitted the user data 8 times with variousredundancy versions.

In some embodiments, four sub-frames after the first transmission (i.e.,sub-frame 8) the UE may receive a NACK on the PHICH. Then, at sub-frame12 (i.e., four sub-frames after receiving the NACK on the PHICH), the UEmay again send two consecutive transmissions. Thus, the UE may transmit2 times in 8 sub-frames.

In some embodiments, the UE may not monitor the PHICH in betweentransmissions and may only monitor the PHICH at sub-frame 36 in order tofurther conserve power. In another embodiment the UE may determinewhether a signal-to-interference-plus noise ratio (SINR) for a channelbetween the base station and the UE is greater than or equal to athreshold. In such embodiments, if the UE determines that the SINR isbelow the threshold, the UE may not transmit in consecutive sub-framesand may instead transmit in only 1 sub-frame out of 8. However, if theSINR is greater than or equal to the threshold, the UE may continue totransmit in consecutive sub-frames and transmit in 2 sub-frames out of 9as described above.

FIGS. 15-16: TTI-Bundling

FIGS. 15 and 16 illustrate a method for distributed TTI bundling,according to some embodiments. The method may include the signalingoperations between a base station, such as eNB 102, and a userequipment, such as UE 106, shown in FIG. 15. Note that the method mayalso include any subset of the features, elements and embodimentsdescribed above.

As shown, at 620 the UE may determine that it has data (e.g., firstinformation) available in its buffer and a regular BSR (buffer statusreport) may be triggered. Thus if the UE has data to transmit to thebase station, the BSR is triggered. Here it is presumed that the UE ispeak current limited and hence is not able to transmit continuously inthe UL. For example, the UE may be only able to perform UL transmissionswith a low duty cycle. One example of a low duty cycle is 30% or less.In some embodiments, the UE is capable of transmission during only oneout of ten sub-frames, i.e., it can transmit during one sub-frame andremains silent for the next 9 sub-frames, resulting in a duty cycle of10%. In other embodiments, the UE may be capable of transmission duringonly one out of 8 sub-frames or one out of 4 sub-frames. Additionally,in certain embodiments, the UE may be capable of transmitting in two orthree sub-frames out of a group of sub-frames. For example, the UE mayutilize TTI-bundling as described herein and transmit in contiguoussub-frames for a single HARQ process. As another example, the UE maytransmit in multiple sub-frames in support of multiple uplink HARQprocesses as described herein.

At 625, if the UE does not have UL resources it will send an SR(scheduling request) to the base station). The SR may request to begin aUL transmission at a prescribed time, such as TTI (0). Prior to sendingthe SR to the base station, e.g., upon joining with the base station,the UE may signal the base station that it is peak current limited, andhence may have a low transmission duty cycle. The base station will thenensure that the SR and SRS transmitted by the UE are aligned. In otherwords, upon learning that the UE is peak current limited, the basestation may ensure that the UE operates such that the periodicity of theSR and SRS are aligned. Alternatively, the UE may explicitly signal thebase station that it desires to send one or more sounding referencesymbols (SRS) in the same sub-frame as the scheduling request (SR) sentin 625. Sounding reference symbols are transmitted by the UE to the basestation in the UL to provide the base station an indication of ULchannel quality, and also to convey timing information. Thus, at 625,the UE may transmit the SR and the SRS simultaneously in the samesub-frame. In some embodiments, the duty cycle (periodicity) of SR andSRS is preferably smaller or equal to the duty cycle of the ULtransmission as dictated by the peak current limitation.

In response to receiving the SR at 625, the base station may configurethe bundle size of the distributed transmit time interval based at leastin part on the SRS information, as described below in FIG. 16. In otherwords, the bundle size information may be dynamically determined by thebase station based on current conditions such as the quality of the ULchannel between the UE and the base station and/or the powercharacteristics of the UE. Note that the power characteristics of the UEmay be conveyed by the UE to the base station in an RRC message. Alength of the distributed transmit time interval (TTI) bundling mayeffectively correspond to the maximum number of HARQ retransmissions, asreflected in the maxHARQ-Tx parameter.

The bundle size specifies the number of retransmissions of theredundancy versions. Thus, for example, if the base station determinesthat each redundancy version (RV) should be sent once based on the SRSinformation, then the bundle size would be four. In another example, ifthe base station determines that only three redundancy versions aredesired to receive the transmission, then the bundle size would bethree. As yet another example, if the base station determines that eightredundancy versions are desired, then the four redundancy versions maybe each sent twice for a total of eight.

Additionally, in response to receiving the SR at 625, the base stationmay send an UL grant at 635. The UL grant may be a dynamic and/orpersistent UL grant. In some embodiments, the UL grant may be asemi-persistent UL grant such as a SPS (semi-persistent scheduling) ULgrant. In other words, the uplink grant received from the base stationmay include information specifying periodic uplink grants. Thus, in someembodiments, the periodicity of the UL grants may be based on the dutycycle of the UE transmissions and the bundle size.

In response to receiving the UL grant 635, the UE may send data (e.g.,first information) via an UL transmission using RV 0 at time zerocorresponding to TTI (0) (e.g., at sub-frame 602). In other words, theUE may send the data using a first redundancy version. Then, the UE maywait a period of X milliseconds (X ms) before sending another ULtransmission using RV 2 at 645 (e.g., at sub-frame 614 or 606 dependingon channel conditions), i.e., the UE may send the data using a differentredundancy version. The UE may then proceed to periodically send theremaining transmissions of the bundle every X ms. Thus, at 650, ULtransmission of RV 1 may be sent X ms after UL transmission using RV 2.Similarly, at 655, UL transmission of RV 3 may be sent X ms after ULtransmission using RV 1.

In some embodiments, the UE may send first and second redundancyversions in consecutive sub-frames and then wait a period of Xmilliseconds before sending third and fourth redundancy versions. Forexample, the UE may send RV 0 and RV 2 at sub-frames 0 and 1,respectively and then wait X milliseconds before sending RV 3 and RV 1in sub-frames X+2 and X+3, respectively.

At 660, the base station may send an acknowledge (ACK) or negativeacknowledge (NACK) message. Thus the base station may send only a singleACK/NACK message after all of the RV transmissions of the bundle (thedistributed bundle) have been sent by the UE (and received by the basestation). This may result in increased transmission efficiency for UEsthat are peak current limited. In some embodiments, the UE may notperform retransmission of the UL transmission in response to receiving aNACK. In other words, if none of the RV transmissions of the distributedbundle were received properly by the base station, and the base stationsends a negative acknowledge, the UE may not retransmit the firstinformation.

Additionally, if the UL grant at 635 was a persistent or semi-persistentUL grant, such as a SPS UL grant, the UE may begin transmission of newdata (e.g., second information) via a new distributed TTI bundled ULtransmission X ms after the last UL transmission using RV 3 has beensent at 655. Alternatively, if the UL grant at 635 was dynamic, but nota persistent or semi-persistent UL grant, the base station may send anew UL grant at least X−4 ms after the last retransmission, i.e., withinX−4 ms of the UL transmission of RV 3 at 655. Upon receiving the new ULgrant, the UE may begin transmission of the new data via the newdistributed TTI bundled UL transmission at least X ms after the last ULtransmission of RV 3 has been sent at 655.

As described above with respect to FIG. 15, in some embodiments themethod may use a form of “distributed” TTI bundling (TTI-B). The actualform of one example of distributed TTI bundling is shown in FIG. 16. ForUEs that are peak current and/or power limited and which cannot transmiton consecutive sub-frames, and which hence cannot take advantage oftraditional prior art TTI bundling as shown above in FIG. 5A, thedistributed TTI bundling method described herein (e.g., described inFIG. 15 and illustrated in FIG. 16) allows such UEs to achieve similarbenefits to traditional TTI bundling.

In particular, in the embodiment described above in FIG. 15, the UE maysend multiple non-consecutive (and hence distributed) UL redundancyversion (RV) transmissions of data (e.g., first information) and doesnot receive an ACK/NACK feedback from the base station to retransmituntil all of the non-consecutive RVs have been sent. In other words,instead of sending multiple UL transmissions of (typically different)redundancy versions in consecutive sub-frames (normal TTI bundling asshown if FIG. 5A), the UE may send multiple UL transmissions of(typically different) redundancy versions over multiple non-consecutivesub-frames. As shown in FIG. 16, a single ACK/NACK is generated by thebase station only after all of the redundancy versions have beentransmitted. This enables avoidance of violation of the HARQ timeline inthe UL.

Thus, in some embodiments, the distributed TTI-B may be defined asfollows:

The UE may send the data (e.g., HARQ Process#0) via UL transmissionswith different redundancy versions (RVs) every X ms, where X is theperiodicity of the retransmission. Thus, as shown in FIG. 16, HARQProcess#0 encoded using redundancy version (RV) 0 may be transmitted bythe UE at TTI# (e.g., time) 0. The UE may then wait X sub-frames (e.g.,TTI periods), where each sub-frame corresponds to a unit of time such asone millisecond, before sending HARQ Process#0 encoded using RV 2, thussending the second transmission of the TTI-B in a non-consecutivesub-frame. Further, the UE may wait another X sub-frames prior tosending HARQ Process#0 encoded using RV 3. Similarly, the UE may waitanother X sub-frames prior to sending HARQ Process#0 encoded using RV 1.Thus, the TTI-B may be distributed over 3X sub-frames as shown.Additionally, after sending the HARQ Process#0 encoded using RV 3, theUE may receive an ACK/NACK from the base station. As shown, in someembodiments the UE may not retransmit HARQ Process#0 after receiving aNACK. Furthermore, if the UE received a dynamic or persistent UL grantas described above, the UE may transmit data, e.g., HARQ Process #1 Xsub-frames after transmitting the final RV version of HARQ Process#0.

In some embodiments X may be the round trip time (RTT) of the HARQ. Incurrent LTE specifications, the HARQ RTT is 8 ms and each TTI is 1 ms.Thus, the RV versions may be sent every 8 ms (i.e., every 8 TTIs orsub-frames). In some embodiments, the X ms used corresponds to the dutycycle imposed by the peak current limitation. For example, in someembodiments X=10 ms, and the RV versions of the distributed TTI-B may besent every 10 ms (i.e., every 10 TTIs or sub-frames). It is noted thatother values of X are also contemplated. In one example implementation,the periodicity X may range between 4-12 ms, among other possiblevalues. Additionally, the periodicity X may correspond to a peak currentlimitation of the UE. If X is larger than 8 ms, then the RTT could bechanged and becomes equal to X. For example, if X=10 ms, then RTT mayalso be 10, and the number of HARQ processes is 10.

In another embodiment, the bundle size may correspond to the parametermaxHARQ-Tx as defined by an RRC (radio resource control) messageprovided by the UE to the base station. The maxHARQ-Tx parameter may bedetermined at least in part based on the current uplink channel quality,as indicated by an SRS received by the base station, as well as thecurrent power limitations of the UE. Thus, the base station maydynamically adjust the bundle size based on the channel conditionbetween the base station and the UE and the current power state of theUE. This dynamic bundle size operation is described in greater detailwith respect to FIG. 8. Alternatively, the bundle size may be fixed andmay be further prescribed by the RAT. For example, in current LTEspecifications, the bundle size is fixed at 4.

The base station may send an ACK/NACK feedback only after the last ULHARQ transmission. However, since the maxHARQ-Tx is reached with thelast transmission, a NACK that is received may be ignored by the UEsince, similar to normal HARQ, the HARQ buffer is flushed. Thus, the UEmay proceed to send a second distributed TTI-B (e.g., starting withHARQProcess#1 transmitted at TTI#4X−1) as shown in FIG. 16.

Embodiments of the present disclosure may be realized in any of variousforms. For example some embodiments may be realized as acomputer-implemented method, a computer-readable memory medium, or acomputer system. Other embodiments may be realized using one or morecustom-designed hardware devices such as ASICs. Still other embodimentsmay be realized using one or more programmable hardware elements such asFPGAs.

In some embodiments, a non-transitory computer-readable memory mediummay be configured so that it stores program instructions and/or data,where the program instructions, if executed by a computer system, causethe computer system to perform a method, e.g., any of a methodembodiments described herein, or, any combination of the methodembodiments described herein, or, any subset of any of the methodembodiments described herein, or, any combination of such subsets.

In some embodiments, a device (e.g., a UE 106) may be configured toinclude a processor (or a set of processors) and a memory medium, wherethe memory medium stores program instructions, where the processor isconfigured to read and execute the program instructions from the memorymedium, where the program instructions are executable to implement amethod, e.g., any of the various method embodiments described herein(or, any combination of the method embodiments described herein, or, anysubset of any of the method embodiments described herein, or, anycombination of such subsets). The device may be realized in any ofvarious forms.

Although the embodiments above have been described in considerabledetail, numerous variations and modifications will become apparent tothose skilled in the art once the above disclosure is fully appreciated.It is intended that the following claims be interpreted to embrace allsuch variations and modifications.

Further Embodiments

In some embodiments, a user equipment device (UE), may include at leastone antenna, at least one radio, and one or more processors coupled tothe at least one radio. The at least one radio may be configured toperform cellular communication using at least one radio accesstechnology (RAT). Additionally, the one or more processors and the atleast one radio may be configured to perform voice and/or datacommunications.

The UE may be configured to communicate to a base station, a number ofuplink (UL) hybrid automatic repeat request (HARQ) processes supportedby the UE, receive first information from the base station in at least afirst sub-frame, and send second information to the base station Xsub-frames after the first sub-frame. The first information maycorrespond to at least a first downlink (DL) HARQ process and a numberof DL HARQ processes may depend upon the number of UL HARQ processes. Inaddition, the second information may comprise a first ACK/NACKassociated with the first DL HARQ process.

In some embodiments, the UE, to communicate the number of UL HARQprocesses supported by the UE, may be further configured to send a firstmessage to the base station and the first message may comprise thenumber of UL HARQ processes supported by the UE. In some embodiments,the UE, to send the first message, may be further configured to send thefirst message via a medium access control (MAC) layer control element(CE).

In some embodiments, the UE, to communicate the number of UL HARQprocesses supported by the UE, may be further configured to determine,based on at least one metric, the number of UL HARQ processes supportedand send the number of UL HARQ processes supported to the base station.In some embodiments, the at least one metric may comprise power headroomand to determine the number of UL HARQ processes, the UE may comparedetermined power headroom to a first threshold. In some embodiments, ifthe determined power headroom is less than the first threshold, the UEmay support one UL HARQ process and if the determined power headroom isgreater than a second threshold, the UE may support two UL HARQprocesses. In some embodiments, the at least one metric may comprise oneor more of UL block error ratio (BLER) and UL signal to interferenceplus noise ratio (SINR).

In some embodiments, the number of UL HARQ processes may be equal to thenumber of DL HARQ processes. In some embodiments, the number of UL HARQprocesses may not be equal to the number of DL HARQ processes. In someembodiments, the number of DL HARQ processes may be further dependentupon DL channel conditions and, in some embodiments, if the DL channelconditions are below a first threshold, the first information maycomprise a plurality of redundancy versions of first data. In suchembodiments, to receive the first information, the UE may be furtherconfigured to receive the plurality of redundancy version in consecutivesub-frames, and the first data may be associated with the first DL HARQprocess. In addition, the UE may have a transmit duty cycle of Xsub-frames and may support only the first DL HARQ process and a UL HARQprocess.

In some embodiments, if the DL channel conditions are above a firstthreshold, the first information may comprise a plurality of DL HARQprocesses. In such embodiments, the UE, to receive the firstinformation, may be further configured to receive the plurality of DLHARQ processes in consecutive sub-frames. In addition, the UE may befurther configured to send an ACK/NACK corresponding to each DL HARQprocess and each corresponding ACK/NACK may be sent X sub-frames after asub-frame in which each DL HARQ process was received. In suchembodiments, the UE, to send an ACK/NACK corresponding to each DL HARQprocess, may be further configured to include a first ACK/NACK for atleast one of the plurality of DL HARQ processes on a payload of seconddata associated with a first UL HARQ process and send a second ACK/NACKfor at least one other of the plurality of DL HARQ processes on aphysical uplink control channel (PUCCH). The second data and the firstACK/NACK may be sent on a physical uplink shared channel (PUSCH). Inaddition, a power to transmit on the PUCCH may be lower than a power totransmit on the PUSCH.

In some embodiments, the UE, to send the second information, may befurther configured to send the second information on a physical uplinkcontrol channel (PUCCH) using format 3.

In some embodiments, a method may include a UE performing communicating,to a base station, a number of uplink (UL) hybrid automatic repeatrequest (HARQ) processes supported by the UE, receiving firstinformation from the base station in at least a first sub-frame, andsending second information to the base station X sub-frames after thefirst sub-frame. The first information may correspond to at least afirst downlink (DL) HARQ process and a number of DL HARQ processesdepends upon the number of UL HARQ processes. The second information maycomprise a first ACK/NACK associated with the first DL HARQ process.

In some embodiments, communicating the number of UL HARQ processessupported by the UE may comprise the UE performing sending a firstmessage to the base station and the first message may comprise thenumber of UL HARQ processes supported by the UE. Additionally, sendingthe first message may comprise the UE performing sending the firstmessage via a medium access control (MAC) layer control element (CE).

In some embodiments, communicating the number of UL HARQ processessupported by the UE may comprise the UE performing determining, based onat least one metric, the number of UL HARQ processes supported andsending the number of UL HARQ processes supported to the base station.In some embodiments, the at least one metric may comprise powerheadroom, wherein determining the number of UL HARQ processes maycomprise the UE performing comparing determined power headroom to afirst threshold. Additionally, if the determined power headroom is lessthan the first threshold, the UE may support one UL HARQ process and ifthe determined power headroom is greater than a second threshold, the UEmay support two UL HARQ processes. In some embodiments, the at least onemetric may comprise one or more of UL block error ratio (BLER) and ULsignal to interference plus noise ratio (SINR).

In some embodiments, the number of UL HARQ processes may be equal to thenumber of DL HARQ processes. In some embodiments, the number of UL HARQprocesses may be not equal to the number of DL HARQ processes. In someembodiments, the number of DL HARQ processes may be further dependentupon DL channel conditions. In some embodiments, if the DL channelconditions are below a first threshold, the first information maycomprise a plurality of redundancy versions of first data and receivingthe first information may comprise the UE performing receiving theplurality of redundancy version in consecutive sub-frames. Additionally,the first data may be associated with the first DL HARQ process. In someembodiments, the UE may have a transmit duty cycle of X sub-frames, andwherein the UE supports only the first DL HARQ process and a UL HARQprocess. In some embodiments, if the DL channel conditions are above afirst threshold, the first information may comprise a plurality of DLHARQ processes and receiving the first information may comprise the UEperforming receiving the plurality of DL HARQ processes in consecutivesub-frames. In such embodiments, the method further may comprise the UEperforming sending an ACK/NACK corresponding to each DL HARQ process andeach corresponding ACK/NACK may be sent X sub-frames after a sub-framein which each DL HARQ process was received. In such embodiments, sendingan ACK/NACK corresponding to each DL HARQ process may comprise the UEperforming including a first ACK/NACK for at least one of the pluralityof DL HARQ processes on a payload of second data associated with a firstUL HARQ process and sending a second ACK/NACK for at least one other ofthe plurality of DL HARQ processes on a physical uplink control channel(PUCCH). The second data and the first ACK/NACK may be sent on aphysical uplink shared channel (PUSCH) and a power to transmit on thePUCCH may be lower than a power to transmit on the PUSCH.

In some embodiments, sending the second information may comprise the UEperforming sending the second information on a physical uplink controlchannel (PUCCH) using format 3.

In some embodiments, a base station may be configured to performwireless communication with a wireless device and may comprise a radioand a processing element operatively coupled to the radio.

In some embodiments, the base station may be configured to receive, froma wireless device, a number of uplink (UL) hybrid automatic repeatrequest (HARQ) processes supported by the wireless device, send firstinformation to the wireless device in at least a first sub-frame, andreceive second information to the base station X sub-frames after thefirst sub-frame. The first information may correspond to at least afirst downlink (DL) HARQ process and wherein the second information maycomprise a first ACK/NACK associated with the first DL HARQ process. Anumber of DL HARQ processes may depend upon the number of UL HARQprocesses.

In some embodiments, the base station, to receive the number of UL HARQprocesses supported by the wireless device, may be further configured toreceive a first message from the wireless device and the first messagemay comprise the number of UL HARQ processes supported by the wirelessdevice. In some embodiments, to receive the first message, the basestation may be further configured to receive the first message via amedium access control (MAC) layer control element (CE).

In some embodiments, the base station, to receive the number of UL HARQprocesses supported by the wireless device, may be further configured toreceive at least one metric from the wireless device and determine,based on the at least one metric, the number of UL HARQ processessupported by the wireless device. The at least one metric may comprisepower headroom and to determine the number of UL HARQ processes, thebase station may be configured to compare determined power headroom to afirst threshold. Additionally, in some embodiments, if the determinedpower headroom is less than the first threshold, the wireless device maysupport one UL HARQ process and if the determined power headroom isgreater than a second threshold, the wireless device may support two ULHARQ processes. In some embodiments, the at least one metric maycomprise one or more of UL block error ratio (BLER) and UL signal tointerference plus noise ratio (SINR).

In some embodiments, the number of UL HARQ processes may be equal to thenumber of DL HARQ processes. In some embodiments, the number of UL HARQprocesses may be not equal to the number of DL HARQ processes. In someembodiments, the number of DL HARQ processes may be further dependentupon DL channel conditions. Additionally, if the DL channel conditionsare below a first threshold, the first information may comprise aplurality of redundancy versions of first data. Further, to send thefirst information, the base station may be further configured to sendthe plurality of redundancy version in consecutive sub-frames and thefirst data may be associated with the first DL HARQ process. In someembodiments, the wireless device may have a transmit duty cycle of Xsub-frames and the wireless device supports only the first DL HARQprocess and a UL HARQ process.

In some embodiments, if the DL channel conditions are above a firstthreshold, the first information may comprise a plurality of DL HARQprocesses and to send the first information, the base station may befurther configured to send the plurality of DL HARQ processes inconsecutive sub-frames. In such embodiments, the base station may befurther configured to receive an ACK/NACK corresponding to each DL HARQprocess, wherein each corresponding ACK/NACK may be received Xsub-frames after a sub-frame in which each DL HARQ process was sent.Further, to receive an ACK/NACK corresponding to each DL HARQ process,the base station may be further configured to receive, on a physicaluplink shared channel (PUSCH), a first ACK/NACK for at least one of theplurality of DL HARQ processes on a payload of second data associatedwith a first UL HARQ process and receive a second ACK/NACK for at leastone other of the plurality of DL HARQ processes on a physical uplinkcontrol channel (PUCCH).

In some embodiments, to receive the second information, the base stationmay be further configured to receive the second information on aphysical uplink control channel (PUCCH) using format 3.

In some embodiments, a method may comprise a base station performingreceiving, from a wireless device, a number of uplink (UL) hybridautomatic repeat request (HARQ) processes supported by the wirelessdevice, sending first information from the base station in at least afirst sub-frame, and receiving second information to the base station Xsub-frames after the first sub-frame. The first information maycorrespond to at least a first downlink (DL) HARQ process, a number ofDL HARQ processes may depend upon the number of UL HARQ processes, andthe second information may comprise a first ACK/NACK associated with thefirst DL HARQ process.

In some embodiments, a user equipment device (UE), may include at leastone antenna, at least one radio, and one or more processors coupled tothe at least one radio. The at least one radio may be configured toperform cellular communication using at least one radio accesstechnology (RAT). Additionally, the one or more processors and the atleast one radio may be configured to perform voice and/or datacommunications.

In some embodiments, the UE may have a transmit duty cycle of Xsub-frames and may be configured to transmit first user data and a firstacknowledge/negative acknowledge (ACK/NACK) in a first sub-framesubsequent to receiving first data from a base station Y sub-framesprior and transmit second user data and a second ACK/NACK in a secondsub-frame subsequent to receiving second data from the base station Ysub-frames prior. The first ACK/NACK may correspond to the first datafrom the base station and X may be greater than Y. The second ACK/NACKmay correspond to the second data from the base station and the secondsub-frame may be X sub-frames after the first sub-frame.

In some embodiments, X may be two times Y. In some embodiments, Y may be4 sub-frames and the UE may be further configured to transmit andreceive using frequency division duplexing.

In some embodiments, X may be the sum of Y and Z, Y may be a number ofsub-frames between receive and transmit and Z may be a number ofsub-frames between transmit and receive. In such embodiments, X may be10 sub-frames and the UE may be further configured to transmit andreceive using time division duplexing. In some embodiments, Y and Z maybe not equal.

In some embodiments, the first and second user data may be transmittedon a physical uplink shared channel (PUSCH), the first and secondACK/NACKs may be transmitted on a physical uplink control channel(PUCCH), and the PUSCH and PUCCH may be aligned.

In some embodiments, the first data may comprise first information andthe second data comprise second information and a third ACK/NACK. Thethird ACK/NACK may correspond to the first user data. In addition, thefirst and second user data may be transmitted on a physical uplinkshared channel (PUSCH), the first and second ACK/NACKs may betransmitted on a physical uplink control channel (PUCCH), the PUSCH andPUCCH may be aligned, second information may be received on a physicaldownlink shared channel (PDSCH), the third ACK/NACK may be received on aphysical hybrid automatic repeat request (HARD) indicator channel(PHICH), the PDSCH and PHICH may be aligned, and PUCCH and the PHICH maybe offset by X sub-frames.

In some embodiments, the UE may be further configured to receive up toY−1 redundancy versions of the first data in consecutive sub-framesprior to receiving the first data and receive up to Y−1 redundancyversions of the second data in consecutive sub-frames prior to receivingthe second data.

In some embodiments, the UE may be further configured to receive up toY−1 additional data in consecutive sub-frames prior to receiving thefirst data and receive up to Y−1 additional data in consecutivesub-frames prior to receiving the second data. In addition, the seconduser data may comprise the second ACK/NACK and respective ACK/NACKS foreach of the Y−1 additional data. In some embodiments, the secondACK/NACK serves as an ACK/NACK for the second data and the Y−1additional data. The second ACK/NACK may be a NACK if the second data orthe Y−1 additional data may be not successfully received and the secondACK/NACK may be an ACK if all of the second data and the Y−1 additionaldata may be successfully received.

In some embodiments, the transmit duty cycle may correspond to using asingle HARQ process. Additionally, the UE may be further configured tosupport two HARQ processes and transmitting first user data and seconduser data corresponds to a first HARQ process. Further, the UE, for asecond HARQ process, may be configured to transmit third user data and athird ACK/NACK in a third sub-frame subsequent to receiving third datafrom the base station X sub-frames prior, wherein the third ACK/NACKcorresponds to the third data and transmit fourth user data and a fourthACK/NACK in a fourth sub-frame subsequent to receiving fourth data fromthe base station X sub-frames prior, wherein the fourth ACK/NACKcorresponds to the fourth data. The third sub-frame may be twosub-frames after the first sub-frame and the fourth sub-frame may be Xsub-frames after the third sub-frame. In some embodiments, the UE may befurther configured to not transmit in a next sub-frame after receivingdata from the base station.

In some embodiments, a method may include a UE performing transmittingfirst user data and a first acknowledge/negative acknowledge (ACK/NACK)in a first sub-frame subsequent to receiving first data from a basestation Y sub-frames prior and transmitting second user data and asecond ACK/NACK in a second sub-frame subsequent to receiving seconddata from the base station Y sub-frames prior, wherein the secondACK/NACK corresponds to the second data from the base station, andwherein the second sub-frame may be X sub-frames after the firstsub-frame. The first ACK/NACK may correspond to the first data from thebase station and the UE may have a transmit duty cycle of X sub-frames.In some embodiments X may be greater than Y.

In some embodiments, X may be two times Y. In such embodiments, Y may be4 sub-frames and the UE may perform transmitting and receiving usingfrequency division duplexing. Alternatively, X may be 10 sub-frames,wherein the UE performs said transmitting and receiving using timedivision duplexing. In some embodiments, X may be the sum of Y and Z andY may be a number of sub-frames between receive and transmit and Z maybe a number of sub-frames between transmit and receive. In suchembodiments, Y and Z may be not equal.

In some embodiments, transmitting the first user data may comprisetransmitting the first user data on a physical uplink shared channel(PUSCH), transmitting the second user data may comprise transmitting thesecond user data on the PUSCH, transmitting the first ACK/NACK maycomprise transmitting the first ACK/NACK on a physical uplink controlchannel (PUCCH), transmitting the second ACK/NACK may comprisetransmitting the second ACK/NACK on the PUCCH, and the PUSCH and PUCCHmay be aligned.

In some embodiments, the first data may comprise first information andthe second data comprise second information and a third ACK/NACK and thethird ACK/NACK may correspond to the first user data. In someembodiments, transmitting the first user data may comprise transmittingthe first user data on a physical uplink shared channel (PUSCH),transmitting the second user data may comprise transmitting the seconduser data on the PUSCH, transmitting the first ACK/NACK may comprisetransmitting the first ACK/NACK on a physical uplink control channel(PUCCH), transmitting the second ACK/NACK may comprise transmitting thesecond ACK/NACK on the PUCCH, and the PUSCH and PUCCH may be aligned.Further, receiving second information may comprise receiving the secondinformation on a physical downlink shared channel (PDSCH) and receivingthe third ACK/NACK on a physical hybrid automatic repeat request (HARQ)indicator channel (PHICH), and the PDSCH and PHICH may be aligned.Additionally, PUCCH and the PHICH may be offset by X sub-frames.

In some embodiments, the method further may comprise the UE performingreceiving up to Y−1 redundancy versions of the first data in consecutivesub-frames prior to receiving the first data and receiving up to Y−1redundancy versions of the second data in consecutive sub-frames priorto receiving the second data.

In some embodiments, the method further may comprise the UE performingreceiving up to Y−1 additional data in consecutive sub-frames prior toreceiving the first data and receiving up to Y−1 additional data inconsecutive sub-frames prior to receiving the second data. In someembodiments, the second user data may comprise the second ACK/NACK andrespective ACK/NACKS for each of the Y−1 additional data. In someembodiments, the second ACK/NACK may serve as an ACK/NACK for the seconddata and the Y−1 additional data. In some embodiments, the secondACK/NACK may be a NACK if the second data or the Y−1 additional data maybe not successfully received and the second ACK/NACK may be an ACK ifall of the second data and the Y−1 additional data may be successfullyreceived.

In some embodiments, the transmit duty cycle of the UE may correspond toa single HARQ process. In such embodiments, the UE may support two HARQprocesses and transmitting first user data and transmitting second userdata may correspond to a first HARQ process. Additionally, the methodfurther may comprise the UE performing, for a second HARQ process,transmitting third user data and a third ACK/NACK in a third sub-framesubsequent to receiving third data from the base station X sub-framesprior and transmitting fourth user data and a fourth ACK/NACK in afourth sub-frame subsequent to receiving fourth data from the basestation X sub-frames prior, wherein the fourth ACK/NACK corresponds tothe fourth data. The third ACK/NACK may correspond to the third data andthe third sub-frame may be two sub-frames after the first sub-frame. Thefourth sub-frame may be X sub-frames after the third sub-frame.

In some embodiments, a non-transitory computer readable memory mediummay store program instructions executable by at least one processor of auser equipment device (UE) to transmit first user data and a firstacknowledge/negative acknowledge (ACK/NACK) in a first sub-framesubsequent to receiving first data from a base station Y sub-framesprior and transmit second user data and a second ACK/NACK in a secondsub-frame subsequent to receiving second data from the base station Ysub-frames prior. The first ACK/NACK may correspond to the first datafrom the base station, the UE may have a transmit duty cycle of Xsub-frames, and X may be greater than Y. The second ACK/NACK maycorrespond to the second data from the base station and the secondsub-frame may be X sub-frames after the first sub-frame.

In some embodiments, a user equipment device (UE), may include at leastone antenna, at least one radio, and one or more processors coupled tothe at least one radio. The at least one radio may be configured toperform cellular communication using at least one radio accesstechnology (RAT). Additionally, the one or more processors and the atleast one radio may be configured to perform voice and/or datacommunications.

The UE may have a transmit duty cycle of X sub-frames and may beconfigured to determine signal-to-interference-plus noise ratio (SINR)for a channel between the UE and a base station and compare the SINR toa threshold. If the SINR is greater than or equal to the threshold, theUE may be configured to transmit, in consecutive sub-frames, a firstversion and a second version of user data and transmit, in consecutivesub-frames, a third version and a fourth version of user data. Further,the transmission of the third version may occur X+1 sub-frames aftertransmission of the first version. If the SINR is less than thethreshold, the UE may be configured to transmit the first version of theuser data in a first sub-frame and transmit the second version of theuser data in a second sub-frame. The second sub-frame may occur Xsub-frames after the first sub-frame.

In some embodiments, if the SINR is greater than or equal to thethreshold, the UE may be further configured to receive a firstacknowledge/negative acknowledge (ACK/NACK) from the base station Ysub-frames after transmitting the second version of the user data andreceive a second ACK/NACK Y sub-frames after transmitting the fourthversion of the user data. Additionally, if the SINR is less than thethreshold, the UE may be further configured to receive the firstACK/NACK from the base station Y sub-frames after transmitting the firstversion of the user data and receive the second ACK/NACK Y sub-framesafter transmitting the second version of the user data. In someembodiments, X may be eight sub-frames and Y may be four sub-frames.

In some embodiments, if the SINR is greater than or equal to thethreshold, the UE may be further configured to enter a connecteddiscontinuous reception cycle (C-DRX) in between consecutivetransmissions and if the SINR is less than the threshold, the UE may befurther configured to enter the C-DRX in between transmissions. Further,the UE may be further configured to receive a first acknowledge/negativeacknowledge (ACK/NACK) from the base station Y sub-frames from an end ofthe C-DRX. In some embodiments, the C-DRX may comprise forty sub-frames.In some embodiments, Y may be four sub-frames.

In some embodiments, a method may comprise a UE performing determiningsignal-to-interference-plus noise ratio (SINR) for a channel between theUE and a base station and comparing the SINR to a threshold. If the SINRis greater than or equal to the threshold, the UE may performtransmitting, in consecutive sub-frames, a first version and a secondversion of user data, wherein the UE may have a transmit duty cycle of Xsub-frames and transmitting, in consecutive sub-frames, a third versionand a fourth version of user data. The third version may occur X+1sub-frames after transmission of the first version. If the SINR is lessthan the threshold, the UE may perform transmitting the first version ofthe user data in a first sub-frame and transmitting the second versionof the user data in a second sub-frame, wherein the second sub-frameoccurs X sub-frames after the first sub-frame.

In some embodiments, if the SINR is greater than or equal to thethreshold, the UE may perform receiving a first acknowledge/negativeacknowledge (ACK/NACK) from the base station Y sub-frames aftertransmitting the second version of the user data and receiving a secondACK/NACK Y sub-frames after transmitting the fourth version of the userdata. Further, if the SINR is less than the threshold, the UE mayperform receiving the first ACK/NACK from the base station Y sub-framesafter transmitting the first version of the user data and receiving thesecond ACK/NACK Y sub-frames after transmitting the second version ofthe user data. In some embodiments, X may be eight sub-frames and Y maybe four sub-frames.

In some embodiments, if the SINR is greater than or equal to thethreshold, the UE may perform entering a connected discontinuousreception cycle (C-DRX) in between consecutive transmissions and if theSINR is less than the threshold, the UE may perform entering the C-DRXin between transmissions. Additionally, the UE may perform receiving afirst acknowledge/negative acknowledge (ACK/NACK) from the base stationY sub-frames from an end of the C-DRX. In some embodiments, the C-DRXmay comprise forty sub-frames. In some embodiments, Y may be foursub-frames.

In some embodiments, a non-transitory computer readable memory mediummay store program instructions executable by at least one processor of auser equipment device (UE) to determine signal-to-interference-plusnoise ratio (SINR) for a channel between the UE and a base station andcompare the SINR to a threshold. If the SINR is greater than or equal tothe threshold, the program instructions may be further executable totransmit, in consecutive sub-frames, a first version and a secondversion of user data, wherein the UE may have a transmit duty cycle of Xsub-frames and transmit, in consecutive sub-frames, a third version anda fourth version of user data. The transmission of the third version mayoccur X+1 sub-frames after transmission of the first version. If theSINR is less than the threshold, the program instructions may be furtherexecutable to transmit the first version of the user data in a firstsub-frame and transmit the second version of the user data in a secondsub-frame. The second sub-frame may occur X sub-frames after the firstsub-frame.

What is claimed is:
 1. A user equipment device (UE), comprising: atleast one antenna; at least one radio, wherein the at least one radio isconfigured to perform cellular communication using at least one radioaccess technology (RAT); one or more processors coupled to the at leastone radio, wherein the one or more processors and the at least one radioare configured to perform voice and/or data communications; wherein theone or more processors are configured to cause the UE to: communicate,to a base station, a number of uplink (UL) hybrid automatic repeatrequest (HARQ) processes supported by the UE; receive first informationfrom the base station in at least a first sub-frame, wherein the firstinformation corresponds to at least a first downlink (DL) HARQ process,wherein a number of DL HARQ processes depends upon the number of UL HARQprocesses supported by the UE, wherein if DL channel conditions arebelow a first threshold, the first information comprises a plurality ofredundancy versions of first data associated with the first DL HARQprocess, and wherein the plurality of redundancy versions are receivedin consecutive sub-frames; and transmit second information to the basestation X sub-frames after the first sub-frame, wherein the secondinformation comprises a first acknowledgement/negative acknowledgment(ACK/NACK) associated with the first DL HARQ process, wherein X is lessthan or equal to
 12. 2. The UE of claim 1, wherein to communicate thenumber of UL HARQ processes supported by the UE, the one or moreprocessors are further configured to cause the UE to: transmit a firstmessage to the base station, wherein the first message comprises thenumber of UL HARQ processes supported by the UE.
 3. The UE of claim 1,wherein to communicate the number of UL HARQ processes supported by theUE, the one or more processors are further configured to cause the UEto: determine, based on at least one metric, the number of UL HARQprocesses supported by the UE; and transmit the number of UL HARQprocesses supported by the UE to the base station.
 4. The UE of claim 1,wherein the number of UL HARQ processes supported by the UE are equal tothe number of DL HARQ processes.
 5. The UE of claim 1, wherein thenumber of UL HARQ processes supported by the UE are not equal to thenumber of DL HARQ processes.
 6. The UE of claim 1, wherein the number ofDL HARQ processes are further dependent upon DL channel conditions. 7.The UE of claim 1, wherein if the DL channel conditions are above thefirst threshold, the first information comprises a plurality of DL HARQprocesses, wherein to receive the first information, the one or moreprocessors are further configured to cause the UE to receive theplurality of DL HARQ processes in consecutive sub-frames; wherein theone or more processors are configured to cause the UE to: transmit anACK/NACK corresponding to each DL HARQ process, wherein eachcorresponding ACK/NACK is sent X sub-frames after a sub-frame in whicheach DL HARQ process was received.
 8. An apparatus comprising: a memory;and a processing element in communication with the memory, wherein theprocessing element is configured to: communicate, to a base station, anumber of supported uplink (UL) hybrid automatic repeat request (HARQ)processes; receive first information from the base station in at least afirst sub-frame, wherein the first information corresponds to at least afirst downlink (DL) HARQ process, wherein a number of DL HARQ processesdepends upon the number of supported UL HARQ processes, wherein if DLchannel conditions are below a first threshold, the first informationcomprises a plurality of redundancy versions of first data associatedwith the first DL HARQ process, and wherein the plurality of redundancyversions are received in consecutive sub-frames; and generateinstructions to transmit second information to the base station Xsub-frames after the first sub-frame, wherein the second informationcomprises a first acknowledgement/negative acknowledgment (ACK/NACK)associated with the first DL HARQ process, wherein X is less than orequal to
 12. 9. The apparatus of claim 8, wherein to communicate thenumber of supported UL HARQ processes, the processing element is furtherconfigured to: generate instructions to transmit a first message to thebase station, wherein the first message comprises the number ofsupported UL HARQ processes.
 10. The apparatus of claim 8, wherein tocommunicate the number of supported UL HARQ processes, the processingelement is further configured to: determine, based on at least onemetric, the number of supported UL HARQ processes; and generateinstructions to transmit the number of supported UL HARQ processes tothe base station.
 11. The apparatus of claim 8, wherein the number ofsupported UL HARQ processes are equal to the number of DL HARQprocesses.
 12. The apparatus of claim 8, wherein the number of supportedUL HARQ processes are not equal to the number of DL HARQ processes. 13.The apparatus of claim 8, wherein the number of DL HARQ processes arefurther dependent upon DL channel conditions.
 14. The apparatus of claim8, wherein if the DL channel conditions are above the first threshold,the first information comprises a plurality of DL HARQ processes,wherein to receive the first information, the processing element isfurther configured to receive the plurality of DL HARQ processes inconsecutive sub-frames; wherein the processing element is configured to:generate instructions to transmit an ACK/NACK corresponding to each DLHARQ process, wherein each corresponding ACK/NACK is sent X sub-framesafter a sub-frame in which each DL HARQ process was received.
 15. Anon-transitory computer readable memory medium storing programinstructions executable by at least one processor of a user equipmentdevice (UE) to: communicate, to a base station, a number of supporteduplink (UL) hybrid automatic repeat request (HARQ) processes; receivefirst information from the base station in at least a first sub-frame,wherein the first information corresponds to at least a first downlink(DL) HARQ process, wherein a number of DL HARQ processes depends uponthe number of supported UL HARQ processes, wherein if DL channelconditions are below a first threshold, the first information comprisesa plurality of redundancy versions of first data associated with thefirst DL HARQ process, and wherein the plurality of redundancy versionsare received in consecutive sub-frames; and generate instructions totransmit second information to the base station X sub-frames after thefirst sub-frame, wherein the second information comprises a firstacknowledgement/negative acknowledgment (ACK/NACK) associated with thefirst DL HARQ process, wherein X is less than or equal to
 12. 16. Thenon-transitory computer readable memory medium of claim 15, wherein tocommunicate the number of supported UL HARQ processes, the programinstructions are further executable to: generate instructions totransmit a first message to the base station, wherein the first messagecomprises the number of supported UL HARQ processes.
 17. Thenon-transitory computer readable memory medium of claim 15, wherein tocommunicate the number of supported UL HARQ processes, the programinstructions are further executable to: determine, based on at least onemetric, the number of supported UL HARQ processes; and generateinstructions to transmit the number of supported UL HARQ processes tothe base station.
 18. The non-transitory computer readable memory mediumof claim 15, wherein the number of DL HARQ processes are furtherdependent upon DL channel conditions.
 19. The non-transitory computerreadable memory medium of claim 15, wherein the number of supported ULHARQ processes are equal to the number of DL HARQ processes.
 20. Thenon-transitory computer readable memory medium of claim 15, wherein thenumber of supported UL HARQ processes are not equal to the number of DLHARQ processes.